Automated fill systems are used for transferring fluids from a reservoir to containers. Typically, these automated systems incorporate a flow meter to accurately control the amount of fluid introduced into each container, either by mass (weight) or volume. These systems are typically used in the pharmaceutical, biopharmaceutical, chemical, and food packaging industries. Likewise, the flow meters can also be used in other industries such as water, waste water, paper, energy, and petrochemical. The automated systems also generally include a stop valve controlled by the flow meter and a nozzle used to transfer the measured amount of fluid to a container.
One type of flow meter commonly used in these automated systems is a mass flow meter that measures flow characteristics based on the controlled generation of Coriolis forces. This type of mass flow meter is known and generally includes a titanium, stainless steel or other durable-material tube that extends centrally through the ends of a hollow enclosed cylinder and that facilitates fluid flow through the cylinder. The enclosed cylinder may contain nitrogen, helium or other suitable gases. To measure the mass flow rate through the tube, the tube is oscillated and, based on the actual measured tube oscillations, the flow characteristics can be computed. For example, when there is no mass flow through the tube, there is no computed phase difference between the applied oscillations and the measured oscillations. When there is mass flow, the tube oscillations is decreased at the inlet and accelerated at the outlet. As the mass flow rate increases, the phase difference also increases. The oscillation of the tube is measured using electrodynamic sensors at the inlet and outlet of the tube.
In many industries, such as pharmaceutical and biopharmaceutical, it is important to clean, sterilize, and validate permanent (i.e., non-disposable process piping) conduits within the system to prevent cross-contamination when the fluid reservoir is changed to introduce a different fluid through the system. This is referred to in the industry as changing batches. When changing batches, it is common to inject cleaning chemicals, pure water, and steam through the conduits to clean and sterilize them. Conduit portions may also have to be disassembled for cleaning and sterilization. Because the tube of the mass flow meter is part of the system, it must also be cleaned and sterilized (or replaced). The cleaning and sterilizing must also be validated prior to proceeding with the next batch. This results in a process that is time consuming, labor intensive and costly due to the associated downtime of the system.
Typically, systems have added additional valves and fittings at multiple locations along the conduits of the system to facilitate a clean-in-place (CIP) or steam-in-place (SIP) process and to allow cleaning and validation over smaller sections of the system. For example, if the entire system cannot be validated, the contamination can be isolated to a specific section and then only that specific section can be re-cleaned. In other words, isolation valves allow one or more sections of the flow path to be cut-off to allow for further cleaning of only the flow path sections that require cleaning. In this manner, isolation valves could be positioned upstream and downstream of the flow meter to define the flow meter tube as one isolated flow path. Although this arrangement simplifies cleaning, sterilizing, and validating between batches, it does not eliminate the costly, labor intensive, and time consuming cleaning process with respect to the flow meter.
Flow meters are also often used in applications that handle and transport caustic and/or corrosive materials (e.g., sewage treatment processes, chemical production processes, and the like). Over time, these harsh materials can corrode or otherwise degrade the tube in the flow meter, thereby requiring replacement of the flow meter. Such replacement is expensive and time consuming.